WASHINGTON (AP) — Bringing their emotional advocacy to the national gun debate, families of those killed in the Connecticut school shooting are appearing with President Barack Obama and walking the halls of Congress to plead for stricter regulations.

They already have helped push through the nation’s most restrictive firearms law, which Gov. Dannel P. Malloy, D-Conn., signed Thursday.

With no lobbying background and fueled by the power of their emotions, a group of Sandy Hook Elementary School families can take credit for helping shape the measure as it moved through the state Legislature.

Now they’re trying to do the same in Washington, where gun legislation is facing tough resistance. Congress is returning from spring break, and Newtown, Conn., families plan to spend the coming week on Capitol Hill.

Their goal of their personal appeals is to speak to every senator who has yet to express support for the gun legislation, and to show how the Dec. 14 shooting has affected their lives.

“I’m not a constitutional scholar and I’m not a Second Amendment specialist,” David Wheeler, who lost his 6-year-old son, Benjamin, said in a telephone interview.

“I don’t know the ins and outs of gun policy but I know …,” his voice trailed off as a sob catches in his throat. “But I now know one of the things that no father should ever know. And in our system of representative government we have to use our voices.”

The families of the 20 children and six staff members killed in the December shooting at Sandy Hook are a diverse group politically.

They include gun owners, and Democrats and Republicans. They don’t always agree on gun policy.

One father — Mark Mattioli, who lost his 6-year-old son, James — attended a National Rifle Association news conference last week to endorse a proposal to train school staffers as armed security officers.

But relatives of nine victims have come together with a nonprofit group called Sandy Hook Promise to sign a letter sent Thursday to senators. It asks them to vote to expand background checks for gun purchases, strengthen laws against gun trafficking and ban ammunition magazines with more than 10 rounds.

Nicole Hockley wonders if her 6-year-old son, Dylan, might be alive if shooter Adam Lanza hadn’t been able to carry 10 magazines that held 30 rounds each into the school that day.

Lanza was able to fire 154 shots during a four-minute rampage in the school. But he stopped shooting briefly in Dylan’s classroom to reload, giving 11 children time to escape.

“They ran for their lives,” Hockley said. “Dylan was not so fortunate. If there were lower capacity magazine clips, there’s a chance Dylan would be here with me today.”

She drives home the point on visits with lawmakers by handing out a photo card — the kind she might have made for a family holiday greeting — with three pictures of her son.

The largest photo shows him wearing a Superman T-shirt. He’s caught in a wide grin that brightens his whole face. “Honor his life,” the card says under the dates, 3/8/06-12/14/12. “Stand with us for change. Now is the time.”

Bill Sherlach passes out a similar card with photos of his wife, Mary, a school psychologist who died as she rushed toward Lanza, trying to stop the shooter. Sherlach said he tells lawmakers about the bravery displayed by his wife and the other school staffers, and he asks, “Can you show the same courage in your vote today?”

As powerful as their personal pain comes across, it may not be enough to overcome Congress’ strong tradition of protecting gun rights. The prospects for barring large-capacity magazines are difficult, and senators have yet to reach a deal to expand background checks.

The Sandy Hook group is not pushing for an assault weapons ban, even though a ban would prohibit the sale of the specific Bushmaster model that Lanza used to kill their loved ones.

The proposed ban is the most politically divisive of Obama’s proposals, in Congress and among Sandy Hook families. Senate leaders say it doesn’t have enough votes to pass, and most of the families don’t support it, either, believing that magazines are more important to prevent a mass shooting. But it has some supporters among the families.

“I don’t think as a realist that you can expect to get to the ultimate on your first foray on this,” Sherlach said. “But we’re not going away.”

Sandy Hook Promise started in the days after the shooting. A group of neighbors came together in their living rooms and decided they wanted to take action to heal the community and aid victims’ families.

They started by helping shovel their driveways and giving funds to those on hard economic times. The nonprofit’s founding members worked their personal and professional connections to figure out how to support public policy, from mental health to gun safety, that could prevent another shooting.

Co-founder Tim Makris left his job at a venture capital firm to become the group’s executive director. “This is not about just guns,” Makris said. “The gun is the enabler, the cause is mental health.”

But right now the issue before Congress is guns.

Sandy Hook families sat in the front row during a March 28 event at the White House, where Obama prodded Congress to pass his proposals.

“Less than 100 days ago that happened, and the entire country was shocked,” Obama said. “And the entire country pledged we would do something about it and that this time would be different. Shame on us if we’ve forgotten. I haven’t forgotten those kids.”

Obama plans to meet with Newtown families Monday when he travels to Connecticut for a speech at the University of Hartford Sports Center, close to the Capitol where the governor signed sweeping new gun restrictions into law Thursday.

The state law requires background checks for all gun sales. It also expanded Connecticut’s assault weapons ban, created a registry of weapons offenders and immediately prohibited the sale of magazines capable of holding more than 10 rounds of ammunition.

Connecticut’s Democratic House speaker, Brendan Sharkey, said the Sandy Hook families pleaded with lawmakers in private meetings to outlaw existing high-capacity magazines, not just the sale of new ones. Sharkey grew emotional in an Associated Press interview as he described how he had to tell them he didn’t have the votes.

“There’s just no way to describe what it’s like when a parent is telling you this gives some — hopefully, some — meaning to their loss of their child and you’re telling them no,” Sharkey said. “They actually apologized for the meeting and for the fact that they put so much pressure. I’m like are you kidding me? These are your children.”

Sharkey said the families suggested a compromise in which owners of the previously purchased high-capacity magazines would have to register them with the state police. It passed.

Nicole Hockley stood over the governor’s left shoulder as he signed the law. The former stay-at-home mom is now putting her marketing career background to work full time for Sandy Hook Promise.

She has met with Vice President Joe Biden, members of Congress and Connecticut lawmakers, although she says she much rather be waiting for Dylan to come home from school each day.

“This is incredibly new to me and certainly not anything I ever expected to be doing in my life,” Hockley said.